Oxidizable organic compositions stabilized with hydrogenated pyrazoles



United States Patent OXIDIZABLE ORGANIC COMPOSITIONS STABI- LIZED WITHHYDROGENATED PYRAZOLES Hermann Gysling, Riehen, near Basel, and HansJakob Peterli, Munchenstein, Basel Land, Switzerland, assignors to J. R.Geigy A.-G., Basel, Switzerland No Drawing. Application June 9, 1958Serial No. 740,542

Claims priority, application Switzerland June 14, 1957 0 Claims. 0252-401 The present invention concerns a process for the stabilising ofsensitive substances. In particular it concerns the protection oforganic substances which are sensitive to oxygen or oxidation from theeffect of oxygen and from the action of addition products thereof onorganic substances. a

It has been found that organic substances which are sensitive to oxygenor oxidation can be protected from the decomposing action of oxygen orfrom oxidation or the effects thereof can be greatly retarded if aslight amount of hydrogenated pyrazoles, aryl substituted in the1-position, wherein the aryl radical may be possibly furthersubstituted, is added to these substances. These compounds correspond tothe general Formulae I and II:

wherein Ar represents an aryl radical and R represents an alkyl radicalor hydrogen.

Examples of organic substances which are sensitive to oxygen oroxidation and which can be stabilised according to the present inventionare hydrocarbons, in particular mineral oils, fats, fatty oils, waxes,ether, aldehydes and all compounds which contain unsaturated organicgroupings, in particular also fatty acids and derivatives thereof aswell as polymers containing unsaturated organic groupings or in whichsuch groupings can easily occur.

In the protective agents of the general Formulae I and 11, Ar representschiefly a phenyl radical. This aryl radical is preferably not furthersubstituted. It can contain however, non-ionogenic substituents inparticular aliphatic groups such as the methyl, ethyl, tert. butyl,tert. pentyl, iso-octyl, dodecyl groups and also ether groups such asmethoxy or ethoxy groups, or halogens such as fluorine, chlorine,bromine, iodine.

In the above formulae, R advantageously represents a lower alkyl radicalhaving 14 C atoms, in particular the methyl radical.

Small amounts of the protective agents are incorporated into thesubstances to be protected, for example in amounts of 0.001 to 1.0% ofthe carrier, the best way of distributing them being dissolving them atusual or raised temperatures.

l-phenyl pyrazolines aliphatically substituted in the 3- and 5-positionshave already been suggested for stabilising turbine oils. Compared withthese l-phenyl pyrazolines used up to now, those used according to thepresent invention surprisingly have a much better and more long lastingaction. This improvement is all the more unobvious as, in the knowncompounds, the break- 2,936,290 Patented May 10, 1960 down of higherside chains leads to less active com pounds.

The anti-oxidative effect of the compounds according to the presentinvention is considerably reduced if they are substituted in the3-position, so that it is important that the 3-position remainsunsubstituted.

The following examples illustrate the action of the 1- aryl-pyrazolinesor l-aryl pyrazolidines used according to the present invention. Wherenot otherwise stated, parts are given as parts by weight. Thetemperatures are given in degrees centigrade. The relationship of partsby weight to parts by volume is as that of grammes to cubic centlmetres.

EXAMPLE 1 Stabilisation of aldehydes Experimental procedure.0.002 g. ofeach of the following stabilisers are added to 20 g. of freshlydistilled enanthol and each mixture, in a shaking vessel connected witha gas measuring tube, is subjected to the action of oxygen. The takcrupof O is continuously registered. Table I shows the result of this test.

TABLE I take-up of Oz in com. Inhibitor 5 hrs. 10 hrs. 20 hrs. 50 hrs.

110119 hydroquinone 0.01% 3 7 15 55 1 phenyl 3.5.5 trimethylpyrazoline0.01% 60 100 1-phenyl-3-isobutenyl- 5-dimethylpyrazoline 0.01% 6 12 26100 l-phenylpyrazollne 0.01% 2 3 6 12 l-phonylpyrazolidine 0.01% 2 2 510 1 (o methoxy phenyl) pyrazoline,

0.01% s 4 s 13 l-(m-chlorophenyl)-pyrazoline, 0.01%. 3 5 10 13l-p-tolyl-pyrazolidine 0.01% 3 4 7 13 I-p-tert.butyl-phenylpyrazoline 1i t'i3t"i"i1 i "fif' 2 3 7 13 --er.uy-p en laZDlllle The test shows thatin concentrations of 0.01% the l-phenylpyrazoline or -pyrazolidine moreeffectively hinders the take-up of oxygen than the stabilisers known inthe state of the art.

It is also remarkable that 3-isobutenyl-5.5-dimethyl-lphenyl-pyrazolineis considerably more efiective than 3-methy1-5.5-dimethyl-1-phenyl-pyrazoline. It is, therefore, completelyunexpected that l-phenyl-pyrazoline again shows a better action than thetrimethyl-pyrazoline and even that its action is more than 10 times thatof 3-isobutenyl-5.5-dimethyl-l-phenyl-pyrazoline.

EXAMPLE 2 Hindering of the peroxide formation in hydrogenated cycles Theaction of the stabilisers with regard to the hindering of peroxideformation in tetrahydronaphthalene in the presence of oxygen is testedwith the apparatus described above. 0.02% of each of the inhibitorsmentioned below are mixed with 20 g. of tetrahydronaphthalene and eachof the mixtures is shaken for 30 hours in an O atmosphere. After thistime, the peroxide formed in each case is determined according to themethod of Wagner, Smith & Peters (Anal. Chem. 19, 976 (1947)).

In Table 2, the amount of n/lO thiosulphate solution needed with thedetermination method mentioned is taken as the measure of the peroxideformation.

TABLE 2 TABLE 5 amount of take-up of O: in ccm.

n/10 thlo- Inhibitor stablliser sulphate 5 needed, 20hrs. 40 hrs.135hrs. 160hrs.

ccm

hydroquinone 32 50 90 100 non 12. 1-phenyl-5-methyl-pyrazoll.ne 2 2 1224 14.1 l-phenyl-B-mct.hyl-pyrazollne 2 50 100 100 hydroq 0. 52l-phenyl--methyl-pyrazolidine 2 3 20 l-phenylpyramline 0.24 10 g s qg ggyg-x g w 8- 5 3150 u my. I e y '1) my pymo e The test shows that, inconcentrations of 0.01%, the

l-phenyl-S-methylpyrazoline or -pyrazolidine used accord- Thls thatl'phenylmgazohne i ing to the present invention more efiectively hinderthe more ectwe t compo s fimher take-up of oxygen than the otherinhibitors mentioned. tuted 1n the pyrazolme ring. What we claim is:

EXAMPLE 3 1. A normally oxidisable organic material selected from thegroup consisting of hydrocarbons, aldehydes Hmdermg of the pemxldeformaflfm m ethers and cyclic ethers stabilised with a compound of oneof 0.01% of each of the following stabllisers are added to th f ltetrahydrofurane and each mixture is left to stand in half CHFCH filledflasks. The peroxide formed is determined by the I t} method describedin Example 2. Table 3 shows the result of these tests.

TABLE 3 amount of N10 Y thlosulphabe stablllser needed per 10 0.0411.tetrahydroiurane, and

cut-( 111. non 115.0 E- H NH hydroquln 1.0 i ifi i h e t h i s fi-dlmeth1 zollne 181 1 tfimitslsobuiena-t.5mmi3 mtra::::::: s12

EXAMPLE 4 Y Retardation of oxidation of lubricating oil Testmethod.Continental Oil Test according to Ind. 40 wherem & Eng.Chemistry, vol. 33, page 339 (1941). R represents a member selected fromthe group con- 13 ccm. of Regal Oil B of Messrs Texas Co. are exsistmgof hydrogen and a lower alkyl radical, and posed to an oxygen atmospherein an apparatus ith t Y represents a member selected from the groupconsistmechanical movement as described in the cited article. ofhydrogen, halogen, alkyl and lower 0 The takeup of 0 is determined bymeasuring the drop p in Pressre h Hg maholheter cohhefited wlth the aPPa2. A normally oxidisable organic material selected ratus. The t me takenuntil the drop m pressure reaches item the group consisting ofhydrocarbons aldehydes 60 1s hh as the cmenoh for the stablhty andcyclic ethers stabilised with l-phenyl-pyrazoline. 0f the Test cohhhohsi3. A normally oxidisable organic material selected 0.05% of coppernaphthenate as ox dat on catalyst and 0 from the group consisting ofhydrocarbons, aldehydes 0.5% of bis-salicylal-l.2-propylene diamine (DuPont and cyclic ethers stabilised with hphenyhsqnethyh metaldeactivator) are added to Regal 011 B and the pyrazohne. whole is subected to the test at 115 C- 4. A normally oxidisable organic materialselected A sample of this o1l WhlCh 1n addition contams 0.25% f thegroup consisting of hydrocarbons, aldehydes and of 1'Phehylpyl:hzohhheas cyclic ethers stabilised with l-phenyl-pyrazolidine. oxidant 1s subected to the same test simultaneously. A normally oxidisable organicmaterial selected The stahlhhes measured were: from the group consistingof hydrocarbons, aldehydes and Hours cyclic ethers stabilisedwithl-phenyl-S-methyl-pyrazoli- Without l-phenylpyrazolme 50 dine il'phehylpyrazohhe 195 6. A normally oxidisable organic material selectedwlth lphehylpyl'azohdlhe 155 from the group consisting of hydrocarbons,aldehydes and Thus, l-phenylpyrazoline as well as l-phenylpyrazolidinecyclic Fibers stabilised with y -ph yhalso proved to be more efiectivestabilisers for the minpyralolmeeral References Cited in the file ofthis ate EXAMPLE 5 UNITED STATES PATENT: at Stabilisation of aldehydes2,160,293 Shoemaker et al May 30, 1939 T m -0.002 g. of each Of thefollowing sta- 2 54 075 Masfin No 16 1948 i l's re ed t0 20 g- Offreshly distilled nonaldehyde 2 515 1 0 copenhaver July 1950 and eachmixture, in a shaking vessel connected with a gas measuring tube, issubjected to the action of oxygen. The take-up of O is continuouslyregistered. Table 5 shows the result of this test:

OTHER REFERENCES Beilstein: Vierte Auflage, Handbuch der OrganischenChemie, vol. 23, page 29.

1. A NORMALLY OXIDISABLE ORGANIC MATERIAL SELECTED FROM THE GROUPCONSISTING OF HYDROCARBONS, ALDEHYDES AND CYCLIC ETHERS STABILISED WITHA COMPOUND OF ONE OF THE FORMULAE: